Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz - Page 63 - diyAudio
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Old 4th December 2014, 07:14 PM   #621
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Quote:
Originally Posted by Eldam View Post
Believe also it worths the "money risk" as it is versatil with input/output and it can match your active crossover goals : with 3 boards you can have your treble/medium/bass with embeded croosover and personal EQ !

I'm hurry to compare it with your AD1862 which is certainly the best R2R chip ever maid (TDA 1541 is not exactly R2R ???), even better with its 20 bits than the PCM 1704 with its 23-24 bits (dryer sound for many !).

Ihmo with OEM chips the best DACchips are TDA1541/AD1862 : first, PCM63 (second, near the ad1862, but not exactly the same, its softer in upermid-treble). Third : pcm1704, AD1865,tda1545A,tda1543....PCM1702...
Yes, I'm actually in for 4 boards, just for versatility sake, in case I'd ever want to build a 4-way speaker system.

The higher order harmonics at 0 dBFS are actually lower with the AD1862 compared to the measurements in the first post in this thread. But at -60 dB the measurements of this discrete dac is the best I've ever seen. Can't miss this opportunity.
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Old 5th December 2014, 04:21 AM   #622
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Originally Posted by andrea_mori View Post
my clock board is a very normal clock, nothing of special, but I think this DAC cannot use any external clock.
And that is the problem.... your clock board is nothing special.

On the other hand Soekris has a R2R DAC design that is unique in the DIY market. That is why there is interest regardless of your opinion of the clocking scheme.

Your comments about Soekris's design sound like the whining of a jealous child who is angry that someone else has stolen the limelight.

Last edited by spzzzzkt; 5th December 2014 at 04:33 AM.
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Old 5th December 2014, 05:40 AM   #623
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Originally Posted by andrea_mori View Post
... single ladder
Why would you want a single ladder? The sign-magnitude architecture is THE key to the design! Without it we would probably get only about 10-bits of monotonicity. Resistors precise enough for 18 bits on a single R2R ladder don't exist on the shelf. My math is bad, but I think you would need something like 0.000000001% resistors for that to work. The sign-magnitude method makes it possible to get a reasonable 18-bits with 0.01% tolerance.
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Old 5th December 2014, 08:46 AM   #624
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Quote:
Originally Posted by spzzzzkt View Post
And that is the problem.... your clock board is nothing special.

On the other hand Soekris has a R2R DAC design that is unique in the DIY market. That is why there is interest regardless of your opinion of the clocking scheme.

Your comments about Soekris's design sound like the whining of a jealous child who is angry that someone else has stolen the limelight.
I think you have a few problem to understand.

First: true, my clock "is nothing special", only 30 dB better than the SiLabs, but maybe you don't understand the difference.
Second: this is not a diy project, you can buy a finished board only, no schematics and so on. Do you think AMR dac are diy project? If yes, ok this is a diy project, otherwise this is not.
Third: my comments are related to this commercial product, exactly like comments about AMR or Wadia products.
And when someone is clearly wrong claiming SiLabs are low jitter oscillator, I have to correct him. No angry or jealous, simply "the datasheet". You can read yourself the Si514 datasheet to discover it's not designed for audio, and it's not a low jitter device.
There are tons of document on the internet that explains phase noise and jitter, I posted some of these several time, please take a look to understand.

Last but not least: my projects are really diy, every schematics are provided, I have no commercial interest.
I do this little thing for the community, not to gain money.
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Old 5th December 2014, 08:48 AM   #625
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@TNT: If you are about to use the NZ2520SDs you might be interested in contacting with this person:

analog.research on eBay

He has done extensive measurements on the NZ2520SDs and apparently there's quite some (up to 30 dBs) difference between the oscillators. To my knowledge he may also sell oscillators with a low (measured) phase noise value.

I know this may be a bit late mentioning this since you have ordered the oscillators ... but maybe of use/interest ...?

Cheers,

Jesper
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Old 5th December 2014, 08:59 AM   #626
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Now - not to "intrude" in a thread that is dedicated to another topic but just briefly:

@andrea_mori:

Quote:
First: true, my clock "is nothing special", only 30 dB better than the SiLabs, but maybe you don't understand the difference.
Hmmm... it somehow surprises me that you say this, Andrea. When comparing the measurements you posted here:

The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator

... with the ones of the Pulsar OCXO it looks to me as if they are the same:

Pulsar Clock - Ultra Low Noise OCXO

Same frequency (11.28 MHz) and close to the same performance. Makes me wonder why you think it's nothing special ...

.... ...

Well, a digression.

Jesper
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Old 5th December 2014, 09:00 AM   #627
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Quote:
Originally Posted by Superdad View Post
Why would you want a single ladder? The sign-magnitude architecture is THE key to the design! Without it we would probably get only about 10-bits of monotonicity. Resistors precise enough for 18 bits on a single R2R ladder don't exist on the shelf. My math is bad, but I think you would need something like 0.000000001% resistors for that to work. The sign-magnitude method makes it possible to get a reasonable 18-bits with 0.01% tolerance.
Sorry, but you are wrong. There is no difference in monotonicity between sign magnitude and other notation. Using 0.01 ladder resistors you can reach 13 bit precision (2^13 = 8192 - 1/8192 * 100 = 0,012%).
There is no "window" that change math analysis due to sign magnitude. When the 14th bit and upper bits switch, the precision decreases.
Using dual ladder you are doubling the error, that's the reason BB used a single ladder in its PCM1704.
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Old 5th December 2014, 09:44 AM   #628
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Quote:
Originally Posted by andrea_mori View Post
I think you have a few problem to understand.

First: true, my clock "is nothing special", only 30 dB better than the SiLabs, but maybe you don't understand the difference.
Second: this is not a diy project, you can buy a finished board only, no schematics and so on. Do you think AMR dac are diy project? If yes, ok this is a diy project, otherwise this is not.
Third: my comments are related to this commercial product, exactly like comments about AMR or Wadia products.
And when someone is clearly wrong claiming SiLabs are low jitter oscillator, I have to correct him. No angry or jealous, simply "the datasheet". You can read yourself the Si514 datasheet to discover it's not designed for audio, and it's not a low jitter device.
There are tons of document on the internet that explains phase noise and jitter, I posted some of these several time, please take a look to understand.

Last but not least: my projects are really diy, every schematics are provided, I have no commercial interest.
I do this little thing for the community, not to gain money.
Andrea, i would back you up on all these aspects. You clock seems quite special!

//
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Old 5th December 2014, 10:42 AM   #629
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Originally Posted by gentlevoice View Post
Now - not to "intrude" in a thread that is dedicated to another topic but just briefly:

@andrea_mori:



Hmmm... it somehow surprises me that you say this, Andrea. When comparing the measurements you posted here:

The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator

... with the ones of the Pulsar OCXO it looks to me as if they are the same:

Pulsar Clock - Ultra Low Noise OCXO

Same frequency (11.28 MHz) and close to the same performance. Makes me wonder why you think it's nothing special ...

.... ...

Well, a digression.

Jesper
Jesper,

I meant nothing of particular at implementation level, maybe "special" was not the appropriate definition.
I meant that my clock can be implemented like any other oscillator such Crystek and so on, just fitting it close to the dac or using u.fl. cable.
Then, there are "commercial projects" like Ian's Fifo buffer that can accommodate external clock (you can also slave it from master clock), while other "commercial projects" like Soekris DAC can't accommodate any external clock.
As I said above, every choice has done by the vendor, so not a diy project.
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Old 5th December 2014, 04:26 PM   #630
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Hi Guys here, please don't dance with him and treat him as air. In Ian's thread, no one gave him any response and then everything went better. Let's focus on Soren's design, maybe it is time for us to discuss digital filter or which output stage can match this R2R Dac better...
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